Application of an alloy in kitchen utensil products

ABSTRACT

The present invention relates to new kitchen utensils, in particular relates to an application of a material in kitchen utensils. The present invention solves the problems of long-term presence in the field. SUS436L is used for kitchen utensils. SUS436L chemical composition (wt %) comprises Cr 16-19, C≦0.025, Si≦1.00, Mn≦1.00, N≦0.02, Ni≦0.60, Ti≦0.75, Mo 0.75-1.50 and balance of Fe. The kitchen utensils have all excellence of present kitchen utensils, overcome its disadvantage and possess high property of heat conduction and magnetoconductivity. The kitchen utensils are used in induction cooker, possess the all and the one structure and have low cost.

TECHNICAL FIELD

The present invention relates to the application of a certain materialin kitchen utensils, and more specifically, to the application of thematerial SUS436L in culinary vessels such as containers, cookware,dishware etc. Particularly, the present invention relates to theapplication in the manufacture of induction cookers and otherkitchenware which requires high heat conductivity andmagnetoconductivity.

BACKGROUND ART

Kitchen utensils, for example, cookware such as boilers and the like,have been developed rapidly, which were early made of iron, aluminum orceramic and gradually superseded by stainless steel that mainly consistsof Cr18Ni9. It is well known that early iron kitchenware is magnetic andprone to rust. Later-developed aluminum one is easy to manufacture andnonmagnetic, however, it should be under surface chemical treatment andoil injection during the manufacture process to obtain certain hardnessand prevent it from oxidation, meanwhile, the inner surface of thiskitchenware should be sprayed with a nonstick coating so that it can beused safely. Cr18Ni9 ( steel type No. 304, called material SUS304 forshort bellow) is a kind of Austenitic Steel, whose chemical composition(WT %) comprises: Cr 17-19, Ni 8-11, C≦0.06, Si≦1.00, Mn≦2.00, S≦0.030,P≦0.035, and the balance of Fe. This material is nonmagnetic, corrosionproof and easy to manufacture. Furthermore, its products are antirust sothat the surface is shiny and beautiful, and can be used in a gasfurnace or an electric cooker. A compound base should be added to thebottom of the products when they are used in induction cookers.

Induction cooker, which makes use of the electromagnetic effect to heatis a stove developed rapidly recently. Since only magnetic materialscould be applied in the induction cooker, generally speaking SUS304itself does not conform to the manufacture of the products used forinduction cooker. However, due to its excellent property in manyaspects, this material can be made into cooking vessel used forinduction cooker if the bottom of the vessel is necessarily covered withmagnetic materials. At present, for example, the steel-aluminum-steelcompound base is in common use, that is, first a layer of aluminum orcopper is soldered on the bottom of the vessel made of the saidmaterial; and then a magnetic stainless steel layer is formed on. Thematerial of steel-aluminum-steel, however, costs high and is hard toprocess. FIG. 1 shows the schematic view of the compound base, whereinmaterial 304 can be used in part A; pure aluminum or copper can be usedin part B; and in part C magnetic metal materials, such as steel 1Cr17(called SUS430 for short, whose chemical composition comprises Cr 16-18,C≦0.12, Si≦0.80, Mn≦0.80, S≦0.030, P≦0.035, Ni≦0.60, trace amount of Moand Ti, and the balance of Fe) and copper etc., can be used.

In order to solve the problem that SUS304 can not be directly used inthe induction cooker, people have been looking for a multifunctionalmaterial to substitute for SUS304, which has the advantages of SUS304and can be applied in manufacture of the products used in the inductioncooker, but always failed. In addition, many materials, such as SUS430,perform badly in manufacture process. It certainly will increase theproduct cost and bring other problems, especially in the manufacture ofdeep-drawing vessels and containers. As a result, many researchers gaveup with no suitable material being found.

SUS436L, which is a kind of Ferritic Steel, comprises in chemicalcomposition (wt %) Cr 17-19, C≦0.025, Si≦1.00, Mn≦1.00, N≦0.02, Ni≦0.60,Ti≦0.75, Mo 0.75-1.50, and the balance of Fe. There is little nickel inthis material, meanwhile, trace amount of molybdenum and titanium areadded in. This material which is mainly used in automobile silencer andexhaust pipe has excellent anticorrosive property and high heatconductivity and magnetoconductivity.

SUMMARY OF THE INVENTION

One of the purposes of the present invention is to research and look fora material that is suitable for kitchen utensils production,particularly suitable for the cookware that requires high heatconductivity and magnetoconductivity. The said cookware can be used ingas furnace, electric cooker or induction cooker.

Another purpose of the present invention is to research and look for amaterial that is suitable for kitchen utensils production, particularlysuitable for the cookware that requires high heat conductivity andmagnetoconductivity and no compound base is needed, i.e. integrativecookware. As a result, the cost of the cookware can be reduced and allthe disadvantages of conventional compound base can be eliminated.

Another purpose of the present invention is to research and look for amaterial that is suitable for kitchen utensils production and theircompound bases. Therefore, the cookware can be added a compound base toform a second base with the same material as required. The cookwareafter this process is better than the one made of steel-aluminum-steelcompound material in performance and eliminates the disadvantages of theconventional compound base materials, such as easy oxidation, poor heatconductivity.

A further purpose of the present invention is to research and look for amaterial that is suitable for kitchen utensils production and has theabove mentioned advantages; moreover, the cost of material andprocessing are relatively low.

Another purpose of the present invention is to research and look for amaterial that is suitable for kitchen utensils production and has theabove mentioned advantages; moreover, can be applied in production ofother kinds of kitchen utensils.

The other purposes and advantages according to the present inventionwill be more apparent by reading the detailed description of theapplication.

The inventor has found, through research, selection, and repeatedexperiments, that the Ferritic Steel with the chemical composition(wt %)of Cr 16-19, C≦0.025, Si≦1.00, Mn≦1.00, N≦0.02, Ni≦0.60, Ti≦0.75, Mo0.75-1.50 and the balance of Fe can be used in the kitchen utensilsproduction and reach all the purposes and requirements of the presentinvention. Typically, this kind of material available in market includesSUS436L (Chinese National Standards). After repeated experiments, theinventor has solved the problems in processing the material SUS436L andtherefore firstly succeeded in applying SUS436L in the field of kitchenutensils production. The SUS436L used in kitchen utensils production hasall the advantages as material SUS304 used in the same, for example, dueto the anticorrosive and magnetic property of this material, it can beapplied in manufacture of integrative products used in induction cooker,gas furnace and electric cooker. In addition, due to the integrativestructure, the cost of the cookware made of this material can bereduced. Moreover, as the material does not contain nickel, it ishelpful to the environment protection and saving energy.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the schematic view of the compound base;

FIG. 2 shows the schematic view of one embodiment according to thepresent invention;

FIG. 3 shows the schematic view of another embodiment according to thepresent invention;

FIG. 4 illustrates the comparison of the anticorrosive propertiesbetween the material applied according to the present invention andother materials.

DETAILED DESCRIPTION OF THE INVENTION

In one aspect of the present invention, it provides kitchen utensilproducts formed by a new type of material. The said kitchen utensilproducts include cookware, dishware and culinary vessels according tothe present invention.

The new type of material used in the present invention comprises inchemical composition as follows (wt %): Cr 16-19, C≦0.025, Si≦1.00,Mn≦1.00, N≦0.02, Ni≦0.60, Ti≦0.75, Mo 0.75-1.50 and the balance of Fe.Typically, this kind of material available in market includes SUS436L.

Comparison of the properties between SUS436L and other materials arelisted in Table 1:

TABLE 1 Heat Conductivity at 100° C. Pitting Potential (W/m ° C.)Magnetoconductivity (mV) SUS436L 23.6 10⁴ 290 SUS304 16.2 1.004 300SUS430 26.1 10⁴ 100

It can be seen from the above data that SUS436L is good at heatconduction and magnetic conduction; and has excellent anticorrosiveproperty.

Comparison of the anticorrosive properties between SUS436L and othermaterials can be seen from the data shown in FIG. 4, from which the sameresult can be concluded as from Table 1.

The process of manufacturing the cookware (in cylindrical shape)according to the present invention includes: 1) Stamping the materialson the punch to form wafers at different diameters depending on theproduct specification desired; 2) Oil Rolling, more oil is used in thisprocess to SUS436L than to material SUS304, due to the lower yieldstrength and elongation of SUS436L; moreover, since SUS436L arerelatively soft and easy to be scratched, more attention to be paid inthe process; 3) Elongation Process, it may be a single elongation or adouble elongation, depending on the desired elongation extent, in whichthe first elongation coefficient can be 0.52˜0.55 while the secondelongation coefficient can be 0.78˜0.8 to form desired dimensions; 4) toform all kinds of shapes according to the requirement; and 5) SurfaceTreatment.

According to another aspect of the present invention, it provides aculinary vessel which is integrative and made of SUS436L. The processincludes: 1) Stamping the materials on the punch to form wafers atdifferent diameters depending on the product specification desired; 2)Oil Rolling, more oil is used in this process to SUS436L than tomaterial SUS304, due to the lower yield strength and elongation ofSUS436L; moreover, since SUS436L are relatively soft and easy to bescratched, more attention to be paid in the process; 3) ElongationProcess, it may be a single elongation or a double elongation, dependingon the desired elongation extent, in which the first elongationcoefficient can be 0.52˜0.55 while the second elongation coefficient canbe 0.78˜0.8 to form desired dimensions; 4) to form all kinds of shapesaccording to the requirement; and 5) Surface Treatment.

It further provides a culinary vessel which has a compound base made ofSUS436L according to another aspect of the present invention. Theprocess to form the compound base includes coating fluxes and solders onthe bottom of the vessel with a sifter after forming the vessel; andthen soldering an aluminum or copper slice with the compound base on thebottom of the vessel by a brazing machine. The compound base may be madeof the same material: SUS436L. During the process of forming thecompound base, special attention should be paid to the control of thesoldering temperature, in which the base to be compounded will beoverheated, causing weld seam, if the temperature is too high.Meanwhile, a cooling ring should be added to the base to avoid thedistortion of the vessel. It also can be made into the impact bondingcooker and the like, whose body and compound base are both made ofSUS436L.

The materials according to the present invention generally are plates,which are changeable in thickness depending on the, for example, 0.4-2.5mm. The height of the vessel 10-600 mm depending on the requirement,preferred 50-320 mm; the diameter of the vessel ranges from 100-600 mm,preferred from 100-360 mm. In addition, the products according to thepresent invention include boilers and dishes, particularly the cookwarewhich requires high heat conductivity and magnetoconductivity.

According to the present invention, the cookware made of SUS436L cancompletely substitute for that made of aluminum or material 304 series.The disadvantages of aluminum products include: 1) they can not be usedin the induction cooker; 2) their surface should be under chemicaltreatment so as to achieve certain hardness and to prevent oxidation; asa result, their longevity are shorter and the products are less ofaesthetics compared with material 436; 3) a nonstick coating should besprayed in the inner surface for being used safely. On the contrary,using the material 436 eliminates all the disadvantages mentioned above,and the property of high heat conductivity and magnetoconductivity playsan effective role in practice. Meanwhile, the inner surface can becoated with a nonstick coating or not depending on the need of themarket.

Embodiments EXAMPLE 1 Manufacture of Integrative Cooker, as Shown inFIG. 2

Model of the boiler: straight body and cut edge cooker with a singlebase

Size: 200*100 mm

Thickness: 2.0 mm

Process in detail:

1) Stamping, press the material on the 100-ton-punch to form a wafer ofΦ360 mm, i.e. a wafer having a diameter Φ=360 mm;

2) Oil Rolling;

3) Single Elongation, the blankholder force is 10 MPa; the angle R ofthe male die is R16, and the angle R of the female die is R10, i.e., themale die has a corner radius R=16 mm, and the female die has a cornerradius R=11 mm;

4) Trimming and Surface Treatment. Then the finished cooker is achieved.

EXAMPLE 2 Cooker with a Compound Base, as Shown in FIG. 3

Model of the boiler: straight body and cut edge cooker with a compoundbase

Size: 240*200 mm

Thickness: 1.0 mm

Process in detail:

1) Stamping the material on the 100-ton-punch to form a wafer of Φ510mm, i.e. a wafer having a diameter Φ=510 mm;

2) Oil Rolling;

3) First elongation, the blankholder force is 10 MPa; the angle R of themale die is R16, and the angle R of the female die is R11, i.e., themale die has a corner radius R=16 mm, and the female die has a cornerradius R=11 mm;

4) Second Elongation, the blankholder force is 5 MPa; the angle R of themale die is R16, and the angle R of the female die is R5; i.e., the maledie has a corner radius R=16 mm, and the female die has a corner radiusR=5 mm;

5) Trimming and Surface Treatment.

6) Forming a compound base (either solderbrazing or impact bonding)

Then the finished cooker is achieved.

Although only two examples are given above, it is appreciated that thepersons skilled in this field may also extend the technology tomanufacture other kinds of cookware according to the disclosure of thisdescription.

1. A process of manufacturing a kitchen utensil from an alloy,comprising the steps of: a. stamping the alloy on a punch to form awafer having a diameter, Φ; b. oil rolling the alloy; c. forming thekitchen utensil using an elongation process on the alloy; and d.trimming and surface treating the formed kitchen utensil, wherein thealloy has a composition (in wt %) consisting of: Cr 16-19, C≦0.025,Si≦1.00, Mn≦1.00, N≦0.02, Ni≦0.60, Ti≦0.75, Mo 0.75-1.50 and the balanceof Fe, wherein the kitchen utensil includes a cookware, dishware andculinary vessel, wherein the cookware is integrative, wherein thekitchen utensil is a straight body and cut edge cooker with a singlebase, wherein the punch is an about 100-ton punch, wherein the diameterΦ of the wafer is about 360 mm, wherein in the elongation process, theblankholder force is about 10 MPa, the angle of the male die is R16 thatcharacterizes the male die having a corner radius R=16 mm, and the angleof the female die is R10 that characterizes the female die having acorner radius R=10 mm.
 2. The process according to claim 1, wherein thealloy is in accordance with SUS436L.
 3. The process according to claim1, wherein the elongation process has an elongation coefficient of in arange of about 0.52-0.55.
 4. A process of manufacturing a kitchenutensil from an alloy, comprising the steps of: a. stamping the alloy ona punch to form a wafer of a diameter, Φ; b. oil rolling the alloy; c.forming the kitchen utensil using an elongation process on the alloy,wherein the elongation process comprises a first elongation process anda second elongation process; and d. trimming and surface treating theformed kitchen utensil, wherein the alloy has a composition (in wt %)consisting of: Cr 16-19, C≦0.025, Si≦1.00, Mn≦1.00, N≦0.02, Ni≦0.60,Ti≦0.75, Mo 0.75-1.50 and the balance of Fe, wherein the kitchen utensilincludes a cookware, dishware and culinary vessel, wherein the cookwarecontains a compound base, wherein the kitchen utensil is a straight bodyand cut edge cooker with a compound base, wherein the punch is an about100-ton punch, wherein the diameter Φ of the wafer is about 510 mm,wherein in the first elongation the blankholder force is about 10 MPa,the angle of the male die is R16 that characterizes the male die havinga corner radius R=16 mm, and the angle of the female die is R11 thatcharacterizes the female die having a corner radius R=11 mm, and whereinin the second elongation, the blankholder force is about 5 MPa, theangle of the male die is R16 that characterizes the male die having acorner radius R=16 mm, and the angle of the female die is R5 thatcharacterizes the female die having a corner radius R=5 mm.
 5. Theprocess according to claim 4, wherein the first elongation has anelongation coefficient of in a range of about 0.52-0.55 and the secondelongation has an elongation coefficient of in a range of about0.78-0.80.